In the known art are various damping devices as disclosed in the following U.S. Pat. Nos.:
2,714,823 issued to A. H. Dall and R. R. Adams on Aug. 9, 1955, showed a frictional vibration damper with an inertia ring with coprene in recesses in the faces and operating under spring bias in a coaxial chamber with a coprene lining. PA1 2,722,138 issued to E. P. Neher on Nov. 1, 1955, showed use of an "O" ring stretched around a perimeter of an inertial ring between it and peripheral flange of a wheel. An adhesive bond was described as unnecessary. PA1 3,264,898 issued to B. E. O'Connor on Aug. 9, 1966, showed a pair of ring-shaped flexible friction pads of Teflon between an inertia ring and a casing; fluid damping was described. PA1 3,334,886 issued to A. Caunt on Aug. 8, 1967, showed a torsional damper using rubber strips. PA1 1. When a mark is applied to the inertia ring and indexed to the hub that is positioned to the shaft, movement of the ring will cause erroneous timing of the assembly during adjustments. PA1 2. These assemblies are generally balanced to 0.25 in. ounces by removing material from the ring after the ring is secured to the hub. Changes in the ring position relative to the hub cause imbalance of the assembly. PA1 3. In severe cases of elastomer and bonding deterioration, the inertia ring can depart from the hub, creating a hazardous rotating missile. PA1 4. Since the bonding or mechanically pressed process of the elastomer require specialized equipment, those assemblies are not field repairable. PA1 1. Replacing the bonded or pressed elastomer with "O" rings, installed between the hub and the inertia ring in a frictional, compressional fit. PA1 2. Fully retaining the inertia ring to the hub with front and retainer plates. PA1 3. Eliminating timing errors by removing the timing reference mark from the inertia ring and applying the mark to a plate or shell that is secured to the hub. PA1 4. Enhancing the ability of the damper to dissipate vibrations by increasing elastomeric material in the outer shell of a damper. PA1 5. Rendering the assembly field-rebuildable by simple replacement of the elastomer. PA1 6. Providing multiple frequency as noted further herein.
However, in the known art no disclosure appears of a damping system with the improvements set forth herein as objects of this invention.
In all internal combustion engines and many mechanical devices, torsional energy is applied to a shaft to transfer energy to the point at which it is used. The torsional energy on the shaft results in a residual twisting of a shaft as it returns to its natural state. These twisting forces create undesirable vibrations or harmonics that will destroy the shaft and related components if permitted to remain in the assembly.
The most commonly used torsional dampers are of the elastomer type. In these dampers a hub is pressed to the shaft, and on the outer diameter of the hub an inertia ring is attached using a bonding or mechanical press process to secure the inertia ring to the hub with a rubber insulation. The rubber insulation allows the inertia ring to move independent of the hub that is pressed on the shaft, the independent movement of the inertia ring dampening torsional vibrations.
Movement of the inertia ring is governed by the stretch of the elastomer used.
These dampers are used exclusively by nearly all major automotive manufacturers as OEM and replacement parts. The bonded or mechanically pressed elastomer securing the inertia ring to the shaft hub deteriorates with age, causing undesirable events to occur: